International Concrete Abstracts Portal

Deteriorating sewer facilities require rapid in-situ rehabilitation and using coating as a corrosion protection is one method currently being adopted. Hence, applicability and performance of coatings under dry and wet conditions must be investigated. Performance of a polymer concrete coating was evaluated using a combination of full scale and laboratory tests. The polyester based polymer concrete coating had a density of 1.75 g/cm3 (109 lb/ft3) and a hardness in the range of 38 to 45 (Barcol hardness). Full-scale test on coating applicability and performance on concrete substrate was performed under a hydrostatic pressure of over 103 kPa (15 psi) of water, simulating the groundwater condition. Coated concrete cylinders and clay bricks with holidays (pinholes) were used to study the chemical resistance under acidic environments to represent the worst sewer and accelerated test conditions (ASTM G 20). Bonding strength between the coating and the concrete and clay brick substrates were determined using the modified ASTM D 4541 and ASTM C 321 tests. Performance of the polymer concrete coating material was studied for over 3 years and the results are analyzed to determine the performance of the polymer concrete coating.

Strengthening and rehabilitation of reinforced concrete structures using externally bonded Fibre Reinforced Polymers (FRP) strips has become a well-established technique with a large research database. Epoxy-modified mortar (EMM) has been used in the industry for more than three decades for various strengthening and rehabilitation purposes. Epoxy modified mortar without a hardener has recently been investigated. The new EMM without a hardener includes polymerlcement ratios as low as 20 percent compared to the 40-60 percent that is usually required to provide suitable mechanical properties of conventional EMM. The new EMM utilizes the cement hydrates to polymerize the epoxy resin in the cement matrix in the absence of a hardener through ring-opening polymerization. The use of ring-opening polymerization provides EMM (without a hardener) with an interesting ability to grow through any developed crack and to repair itself, thus showing enhanced fracture toughness with age. The new self-repair epoxy mortar (SREM) has shown better mechanical performance than the conventional EMM with the same polymer/cement ratio. The objective of this work is to discuss the potential use of SREM to bond FRP laminates to existing concrete substrates in rehabilitation and strengthening applications. A multi-phase research programme examining the different strength, fracture and durability criteria of the SREM-FRP composite is proposed here. Fracture mechanics principles in conjunction with microstmctural investigations will explain and maximize the material ability to self-repair.

Acrylic polymers are widely recognized for their excellent UV durability and water resistance properties. When acrylic polymers are used as modifiers in Portland cement formulations, those polymer properties translate into excellent long-term outdoor durability and wet adhesion durability in the modified concrete. A number of lab prepared series of acrylic polymer modified portland cement formulations have been placed in outdoor exposure and tested periodically for the durability of various properties. Some of these experimental series have been on exposure for as long as 30 years. The results of these studies indicate that acrylic polymers are the ideal cement modifiers with respect to outdoor durability and wet adhesion durability.

The construction, performance and use of polymer concrete bridge overlays over the past 25 years is summarized. Polymer concrete overlays that have an established history of use and acceptance include multiple-layer epoxy, multiple-layer epoxy urethane, methacrylate slurry and premixed polyester styrene. Evaluations indicate that polymer concrete overlays can provide skid resistance and protection against intrusion by chloride ions for 25 years and are an economical technique for extending the life of concrete decks, particularly when overlays must be constructed during off-peak traffic penods to minimize inconvenience to motorists.

The historical development of polymer-impregnated concrete (PIC) is reviewed. Starting in 1965, PIC was developed over a period o f several years as part of a joint research program conducted by the Bureau of Reclamation (USBR) and Brookhaven National Laboratory (BNL) under sponsorship of the USBR, Atomic Energy Commission (ARC), and the Office o f Saline Water (OSW). At various times other organizations funded portions of the program aimed at developing applications directed at their particular interests. Following reports of the research results, research was also conducted by many other organizations in the US and worldwide. The paper reviews the various processes and equipment used to produce both partial and fully impregnated concrete. Included are discussions on drying the concrete, placing it under vacuum, pressure soaking, encapsulation, and polymerization techniques. Monomer and catalyst systems arc also discussed. Costs and safety procedures are also mentioned. Comparisons of improvements in properties of PIC over conventional concrete are given.